Combined Impact of Triglyceride-Glucose Index and Alanine Aminotransferase on Steatotic Liver Disease and Subtypes

Abstract

Background and Aim: The triglyceride-glucose (TyG) index and alanine aminotransferase (ALT) are emerging biomarkers linked to metabolic disturbances and liver health. Nonetheless, the combined impact of these markers on predicting new-onset steatotic liver disease (SLD) and its metabolic and alcohol-associated subtypes remains unclear. This study aimed to investigate the association of TyG and ALT, individually and combined, in incident SLD in the Korean Genome and Epidemiology Study (KoGES) and UK Biobank cohorts. Methods: This study utilized data from two large population-based cohorts: KoGES (adults aged 40-69 years from South Korea [2001-2002]) and UK Biobank (participants aged 37-73 years from the United Kingdom [2006-2010]). Participants without baseline SLD were classified into four groups based on TyG index and ALT levels, and the incidence of SLD was compared among these groups to assess risk. Results: Elevated baseline TyG index and ALT levels were significantly associated with a higher risk of new-onset SLD and its subtypes in both cohorts. The highest HRs and ORs were observed in individuals with both markers elevated (2.39 in KoGES; 3.89 in UK Biobank). Survival analyses confirmed significantly lower survival probabilities in high-risk groups (p < 0.001). Predictive accuracy was highest with the combined TyG index + ALT model, outperforming either marker alone (p < 0.001). Conclusions: Elevated combined baseline TyG index and ALT levels were significantly associated with increased risk of SLD and its subtypes. Combined use of these markers may be valuable for early identification and risk stratification of individuals at risk for SLD.